We have demonstrated that several rhodium(II) carboxylates exhibit potent antitumor activity against Ehrlich ascites tumor carried in Swiss Albino mice. The degree of anticancer activity is dependent on the nature of the carboxylate ligand. For example rhodium(II) butyrate is more potent than the propionate or acetate complexes. The research proposed involves the synthesis of a wide variety of rhodium(II) carboxylates and the determination of the efficacy of these complexes as anticancer agents. Studies are being carried out to determine the nature of the bonding between the rhodium(II) carboxylates and molecules of biological importance. These studies include a thermodynamic and kinetic investigation of the complex formation reactions. The research also includes mechanism of action studies with the rhodium(II) complexes in the Ehrlich system. We plan to correlate the thermodynamic and kinetic data with the degree of anticancer activity and enzyme inhibition produced by the different rhodium(II) carboxylates. This information should aid us in determining the type of rhodium(II) complex that will produce the optimum anticancer activity with the least toxicity.